1. Field of the Invention
The present invention relates to a focused ion beam apparatus including a gas field ion source.
2. Description of the Related Art
As anion source of a focused ion beam apparatus, a gas field ion source which ionizes a material gas and emits an ion beam is known.
As an apparatus which uses a gas field ion source, for example, a focused ion beam apparatus has been proposed which irradiates an argon ion beam from the gas field ion source and performs micromachining such as repairing a defect in a photomask (see International Patent WO2009/022603A1).
However, the apparatus disclosed in International Patent WO2009/022603 has a problem in that, when a sample is observed, the sample is damaged due to the sputtering effect of an argon ion beam. On the other hand, a helium ion beam has a problem in that the etching efficiency is low when a sample is processed, and thus, it takes an enormous amount of time to carry out the processing.